A conventional optical control type phased array antenna includes signal generating means for outputting one electrical signal corresponding to an inputted beam direction of a phased array antenna, and a plurality of phase shifting means for phase-shifting a plurality of first optical signals outputted from second distribution means by phase amounts which correspond to the electrical signal and which are different from one another. Thus, a circuit can be simplified to be reduced in size and weight, and hence the whole phased array antenna including the circuit can be reduced in size and weight (refer to JP-A 3-57305 (page 9 and FIG. 1) for example).
However, there is encountered a problem in that measures for suppressing a phase noise and a relative intensity noise of a light source itself are not taken in the above-mentioned conventional optical control type phased array antenna.
The present invention has been made in order to solve the above-mentioned problem. It is, therefore, an object of the present invention to obtain an optical control type phased array antenna capable of suppressing phase noises including: a phase noise generated by phase fluctuation of a light source itself; a phase noise generated by an optical length change resulting from a change of a refractive index of the atmosphere due to a disturbance such as a temperature fluctuation in a space in a case where a spatial transmission line is used as transmission means; a phase noise generated by a change in beam scanning direction; and a relative intensity noise of the light source.